Correct selection of drilling entry sheet can improve PCB Drilling quality

For PCB drilling, the use of Drilling backup board & entry sheet is to prevent the surface and bottom copper foil of the PCB from blooming and producing burrs

The main function of the?entry sheet

1. Protect the plate surface (protect the copper foil surface of the copper-clad plate, or the copper conductive layer of the substrate) to prevent the pressure foot from crushing the plate surface
2. fixed the drill bit to reduce the swing amplitude and offset of the bit when drilling, so that the bit can be accurately positioned; Improve the accuracy of hole positioning, prevent the bit from breaking
3. Prevent burr of orifice on substrate
4. Assist the bit to dissipate heat and reduce bit temperature
5. Assist in cleaning bit grooves; Prevent greasy dirt hole; Reduce bit wear and breakage, etc

The entry sheet used in China is mainly 0.2 ~ 0.5mm thick phenolic entry board and aluminum foil. Due to the good thermal conductivity and rigidity of aluminum, the aluminum foil has a certain heat dissipation effect on the drill bit. Compared with the phenolic board, the aluminum foil material has no impurities and the probability of breaking the drill bit and partial hole is much less than the phenolic board. Can reduce the temperature of drilling and is a kind of environmental protection material, widely used in many factories have used aluminum foil as the backing plate, at the same time, compared with phenolic plate, epoxy plate, because of the resin contained in the hole may be resin pollution, In the process of use, the thickness of common aluminum foil is chosen as 0.15, 0.20 and 0.30 mm. In the actual use process, the contact between 0.15 and the plate surface is the best, but it is not easy to control the process in the cutting and transportation process and use. The price of 0.30 is a little higher, and the aluminum foil of 0.20 mm is generally used in a compromise. The actual thickness is generally 0.18 mm

At the same time, in order to solve the problem that the surface of alloy aluminum cover plate is too hard and easy to cause the bit to slip, the lubricating aluminum sheet is developed. The aluminum sheet also plays an important role in improving the accuracy of hole position and solving the problem of bit heat dissipation during bit processing. In recent years, the application market of lubricated aluminum sheet has been rapidly expanded. It can be predicted that in the coming years, it is one of the ideal auxiliary materials in micro-hole drilling.

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